The present invention grows out of a continuing development of forging hammer controls. In recent years, forging hammers have increasingly been of the compressible fluid driven type. A device disclosed in U.S. Pat. No. 4,131,164, the invention of Wilmer W. Hague and Charles W. Frame, senses position of the ram, and hence the piston, to make sure that the piston position does not partially occlude the intake port when the inlet valve is opened in order to assure repeatable performance. The impact device of U.S. Pat. No 3,464,315, the invention of Henry A. Weyer, provides pilot valves to control inlet and exhaust valves. U.S. Pat. No. 3,818,799, the invention of Wilmer W. Hague, allows both the number and intensity of the series of blows to be performed by a forging hammer to be preselected. Each of these patents is assigned to the assignee of the present invention, Chambersburg Engineering Company.
These prior art refinements represent important steps along the road to automation and efficiency. However, these developments were accomplished by knowing what the forging device was capable of doing and assuming that it would always perform in precisely the same way, or making correction based upon a single parameter to allow the forging device to perform that way. While this assumption resulted in important improvements over the prior art, the assumption was a generalized one and often subject to error. In fact, many factors enter into the operation of the forging hammer which cause the energy of blows intended to be identical, to vary from one another, depending upon variations in operating parameters.
The advent of computer assisted die design, which prescribes discrete magnitudes of forging energy, demands that forging equipment be capable of delivering precise energies per blow. Developments of this sort have made greater precision in energy control in a forging operation of great significance. The present invention is in response to this need.